I have read that it is better to re use factory ring and pinion gears when re building a rear end that buying aftermarket gears. Something about after market gears being more noisy.
I always thought it was a bad idea to re use gears.
The reason I am asking is the rebuilding of the rear end in a 68 mustang.
You might consider having it done professionally. The set-up can be tricky and might involve shims and "feel".
IF the original gears are in good shape with no noise AND you kept track of the shims and crush sleeve depth, you can reuse the factory gears. You will still need to adjust them a bit because of the new bearings and check the pattern.
BUT what are you going to use it for? Factory ratio in that is probably from 2:80 - 4:10 ratio. (depending on engine/trans combo) You can make a BIG difference in drivability by changing the gearing. Are you restoring it to stock with the same engine/trans that it came with? If not you may want to change the gear ratio to match the new combination.
Rule of thumb for gear ratios: 23 to 25 inch tall tire and an automatic transmission, use a 2:80 to a 3:50 gear ratio. Your rpm range will be around 2,700 with the 2:80 to 3,500 with he 3:50 at 60 mph.
With a manual and the same tires use a 3:50 to 4:11 ratio. Your rpm range will be approximately 2,900 with the 3:50 to 3,500 with the 4:11 at 60 mph.
As for the after market gears being noisy, that depends on which type and ratio gear set you choose and how well you pay attention while installing it. There are a LOT of companies that make gears for the 9"
Yes, I have heard it was tricky. When I was younger, My dad had someone install gears in my car and he could not do it. We had to have someone else do it.
That is part of what makes me want to do it. Is it possible to do a good job if you take your time>?
Sure, it ain't rocket surgery. Have fun! And it'll look good on your resume.
I just read through the factory shop manual instructions to rebuild an
8.8" ring gear differential on a 1991 Ranger. The special removal and assembly tools don't look too hard to machine if you can't borrow them. I've made several tools from descriptions in the manual. The critical parts of the gauge for determining pinion shims are a disk 1.1884" thick, an aligning adapter 1.612" O.D., a gauge tube 3.0630" O.D., and an L shaped block 1.700" thick.It warns that the pinion oil seal -must- be installed with the correct tool.
-jsw
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